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2013


Probabilistic Object Tracking Using a Range Camera
Probabilistic Object Tracking Using a Range Camera

Wüthrich, M., Pastor, P., Kalakrishnan, M., Bohg, J., Schaal, S.

In IEEE/RSJ International Conference on Intelligent Robots and Systems, pages: 3195-3202, IEEE, November 2013 (inproceedings)

Abstract
We address the problem of tracking the 6-DoF pose of an object while it is being manipulated by a human or a robot. We use a dynamic Bayesian network to perform inference and compute a posterior distribution over the current object pose. Depending on whether a robot or a human manipulates the object, we employ a process model with or without knowledge of control inputs. Observations are obtained from a range camera. As opposed to previous object tracking methods, we explicitly model self-occlusions and occlusions from the environment, e.g, the human or robotic hand. This leads to a strongly non-linear observation model and additional dependencies in the Bayesian network. We employ a Rao-Blackwellised particle filter to compute an estimate of the object pose at every time step. In a set of experiments, we demonstrate the ability of our method to accurately and robustly track the object pose in real-time while it is being manipulated by a human or a robot.

am

arXiv Video Code Video DOI Project Page [BibTex]

2013


arXiv Video Code Video DOI Project Page [BibTex]


3-D Object Reconstruction of Symmetric Objects by Fusing Visual and Tactile Sensing
3-D Object Reconstruction of Symmetric Objects by Fusing Visual and Tactile Sensing

Illonen, J., Bohg, J., Kyrki, V.

The International Journal of Robotics Research, 33(2):321-341, Sage, October 2013 (article)

Abstract
In this work, we propose to reconstruct a complete 3-D model of an unknown object by fusion of visual and tactile information while the object is grasped. Assuming the object is symmetric, a first hypothesis of its complete 3-D shape is generated. A grasp is executed on the object with a robotic manipulator equipped with tactile sensors. Given the detected contacts between the fingers and the object, the initial full object model including the symmetry parameters can be refined. This refined model will then allow the planning of more complex manipulation tasks. The main contribution of this work is an optimal estimation approach for the fusion of visual and tactile data applying the constraint of object symmetry. The fusion is formulated as a state estimation problem and solved with an iterative extended Kalman filter. The approach is validated experimentally using both artificial and real data from two different robotic platforms.

am

Web DOI Project Page [BibTex]

Web DOI Project Page [BibTex]


Learning and Optimization with Submodular Functions
Learning and Optimization with Submodular Functions

Sankaran, B., Ghazvininejad, M., He, X., Kale, D., Cohen, L.

ArXiv, May 2013 (techreport)

Abstract
In many naturally occurring optimization problems one needs to ensure that the definition of the optimization problem lends itself to solutions that are tractable to compute. In cases where exact solutions cannot be computed tractably, it is beneficial to have strong guarantees on the tractable approximate solutions. In order operate under these criterion most optimization problems are cast under the umbrella of convexity or submodularity. In this report we will study design and optimization over a common class of functions called submodular functions. Set functions, and specifically submodular set functions, characterize a wide variety of naturally occurring optimization problems, and the property of submodularity of set functions has deep theoretical consequences with wide ranging applications. Informally, the property of submodularity of set functions concerns the intuitive principle of diminishing returns. This property states that adding an element to a smaller set has more value than adding it to a larger set. Common examples of submodular monotone functions are entropies, concave functions of cardinality, and matroid rank functions; non-monotone examples include graph cuts, network flows, and mutual information. In this paper we will review the formal definition of submodularity; the optimization of submodular functions, both maximization and minimization; and finally discuss some applications in relation to learning and reasoning using submodular functions.

am

arxiv link (url) [BibTex]

arxiv link (url) [BibTex]


Hypothesis Testing Framework for Active Object Detection
Hypothesis Testing Framework for Active Object Detection

Sankaran, B., Atanasov, N., Le Ny, J., Koletschka, T., Pappas, G., Daniilidis, K.

In IEEE International Conference on Robotics and Automation (ICRA), May 2013, clmc (inproceedings)

Abstract
One of the central problems in computer vision is the detection of semantically important objects and the estimation of their pose. Most of the work in object detection has been based on single image processing and its performance is limited by occlusions and ambiguity in appearance and geometry. This paper proposes an active approach to object detection by controlling the point of view of a mobile depth camera. When an initial static detection phase identifies an object of interest, several hypotheses are made about its class and orientation. The sensor then plans a sequence of view-points, which balances the amount of energy used to move with the chance of identifying the correct hypothesis. We formulate an active M-ary hypothesis testing problem, which includes sensor mobility, and solve it using a point-based approximate POMDP algorithm. The validity of our approach is verified through simulation and experiments with real scenes captured by a kinect sensor. The results suggest a significant improvement over static object detection.

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pdf [BibTex]

pdf [BibTex]


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Action and Goal Related Decision Variables Modulate the Competition Between Multiple Potential Targets

Enachescu, V, Christopoulos, Vassilios N, Schrater, P. R., Schaal, S.

In Abstracts of Neural Control of Movement Conference (NCM 2013), February 2013 (inproceedings)

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[BibTex]

[BibTex]


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Optimal control of reaching includes kinematic constraints

Mistry, M., Theodorou, E., Schaal, S., Kawato, M.

Journal of Neurophysiology, 2013, clmc (article)

Abstract
We investigate adaptation under a reaching task with an acceleration-based force field perturbation designed to alter the nominal straight hand trajectory in a potentially benign manner:pushing the hand of course in one direction before subsequently restoring towards the target. In this particular task, an explicit strategy to reduce motor effort requires a distinct deviation from the nominal rectilinear hand trajectory. Rather, our results display a clear directional preference during learning, as subjects adapted perturbed curved trajectories towards their initial baselines. We model this behavior using the framework of stochastic optimal control theory and an objective function that trades-of the discordant requirements of 1) target accuracy, 2) motor effort, and 3) desired trajectory. Our work addresses the underlying objective of a reaching movement, and we suggest that robustness, particularly against internal model uncertainly, is as essential to the reaching task as terminal accuracy and energy effciency.

am

PDF [BibTex]

PDF [BibTex]


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Self-Propelled Micromotors for Cleaning Polluted Watter

Soler, L., Magdanz, V., Fomin, V. M., Sanchez, S., Schmidt, O. G.

ACS Nano, 11, pages: 9611-9620, American Chemical Society, Washington, DC, 2013 (article)

Abstract
We describe the use of catalytically self-propelled microjets (dubbed micromotors) for degrading organic pollutants in water via the Fenton oxidation process. The tubular micromotors are composed of rolled-up functional nanomembranes consisting of Fe/Pt bilayers. The micromotors contain double functionality within their architecture, i.e., the inner Pt for the self-propulsion and the outer Fe for the in situ generation of ferrous ions boosting the remediation of contaminated water.The degradation of organic pollutants takes place in the presence of hydrogen peroxide, which acts as a reagent for the Fenton reaction and as main fuel to propel the micromotors. Factors influencing the efficiency of the Fenton oxidation process, including thickness of the Fe layer, pH, and concentration of hydrogen peroxide, are investigated. The ability of these catalytically self-propelled micromotors to improve intermixing in liquids results in the removal of organic pollutants ca. 12 times faster than when the Fenton oxidation process is carried out without catalytically active micromotors. The enhanced reaction\textendashdiffusion provided by micromotors has been theoretically modeled. The synergy between the internal and external functionalities of the micromotors, without the need of further functionalization, results into an enhanced degradation of nonbiodegradable and dangerous organic pollutants at small-scale environments and holds considerable promise for the remediation of contaminated water.

icm

DOI [BibTex]

DOI [BibTex]


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Stability of thin liquid films and sessile droplets under confinement

Dörfler, F., Rauscher, M., Dietrich, S.

Physical Review E, 88(1), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Nonequilibrium interfaces in colloidal fluids

Bier, M., Arnold, D.

Physical Review E, 88(6), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Colloidal particles at fluid interfaces: Effective interactions, dynamics and a gravitation\textendashlike instability

Bleibel, J., Dom\’\inguez, A., Oettel, M.

The European Physical Journal Special Topics, 222(11):3071-3087, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Anomalous transport in the crowded world of biological cells

Höfling, Felix, Franosch, Thomas

Reports on Progress in Physics, 76(4), IOP Pub., London, 2013, author: Höfling, Felix (article)

icm

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Flow pattern in the vicinity of self-propelling hot Janus particles

Bickel, T., Majee, A., Würger, A.

Physical Review E, 88(1), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Brownian motion of optically trapped ellipsoids

Dibak, Manuel

Universität Stuttgart, Stuttgart, 2013 (mastersthesis)

icm

[BibTex]

[BibTex]


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Nonequilibrium Critical Casimir Effect in Binary Fluids

Furukawa, A., Gambassi, A., Dietrich, S., Tanaka, H.

Physical Review Letters, 111(5), American Physical Society, Woodbury, N.Y., 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Many-body effects for critical Casimir forces

Gomes de Mattos, T., Harnau, L., Dietrich, S.

The Journal of Chemical Physics, 138(7), 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Propulsion Mechanism of Catalytic Microjet Engines

Magdanz, V., Fomin, V. M., Soler, L., Sanchez, S., Schmidt, O. G., Hippler, M.

IEEE Transactions on Robotics and Automation, pages: 40-48, IEEE, New York, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Impedance spectroscopy of ions at liquid-liquid interfaces

Bier, M., Reindl, A.

Physical Review E, 88(5), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Precursors of order in aggregates of patchy particles

Vasilyev, O., Klumov, B. A., Tkachenko, A. V.

Physical Review E, 88(1), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Two-temperature Langevin dynamics in a parabolic potential

Dotsenko, V., Maciolek, Anna, Vasilyev, O., Oshanin, G.

Physical Review E, 87(6), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


Fusing visual and tactile sensing for 3-D object reconstruction while grasping
Fusing visual and tactile sensing for 3-D object reconstruction while grasping

Ilonen, J., Bohg, J., Kyrki, V.

In IEEE International Conference on Robotics and Automation (ICRA), pages: 3547-3554, 2013 (inproceedings)

Abstract
In this work, we propose to reconstruct a complete 3-D model of an unknown object by fusion of visual and tactile information while the object is grasped. Assuming the object is symmetric, a first hypothesis of its complete 3-D shape is generated from a single view. This initial model is used to plan a grasp on the object which is then executed with a robotic manipulator equipped with tactile sensors. Given the detected contacts between the fingers and the object, the full object model including the symmetry parameters can be refined. This refined model will then allow the planning of more complex manipulation tasks. The main contribution of this work is an optimal estimation approach for the fusion of visual and tactile data applying the constraint of object symmetry. The fusion is formulated as a state estimation problem and solved with an iterative extended Kalman filter. The approach is validated experimentally using both artificial and real data from two different robotic platforms.

am

DOI Project Page [BibTex]

DOI Project Page [BibTex]


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Critical Casimir forces between homogeneous and chemically striped surfaces

Parisen Toldin, F., Tröndle, M., Dietrich, S.

Physical Review E, 88, American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Comparison between theory and simulations for the magnetization and the susceptibility of polydisperse ferrofluids

Szalai, I., Nagy, S., Dietrich, S.

Journal of Physics: Condensed Matter, 25(46), IOP Pub., Bristol, UK, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Thermal activation of catalytic microjets in blood samples using microfluidic chips.

Soler, L., Mart\’\inez-Cisneros, C., Swiersy, A., Sanchez, S., Schmidt, O. G.

Lab on a Chip, 13, pages: 4299-4303, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Phase behavior of colloidal suspensions with critical solvents

Mohry, T. F.

Universität Stuttgart, Stuttgart, 2013 (phdthesis)

icm

link (url) [BibTex]

link (url) [BibTex]


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Nematic liquid crystal boojums with handles on colloidal handlebodies

Liu, Q. K., Senyuk, B., Tasinkevych, M., Smalyukh, I. I.

Proceedings of the National Academy of Sciences of the United States of America, 110(23):9231-9236, National Academy of Sciences, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Critical Casimir torques and forces acting on needles in two spatial dimensions

Vasilyev, Oleg, Eisenriegler, E., Dietrich, Siegfried

Physical Review E, 88(1), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Dynamical Movement Primitives: Learning Attractor Models for Motor Behaviors

Ijspeert, A., Nakanishi, J., Pastor, P., Hoffmann, H., Schaal, S.

Neural Computation, (25):328-373, 2013, clmc (article)

Abstract
Nonlinear dynamical systems have been used in many disciplines to model complex behaviors, including biological motor control, robotics, perception, economics, traffic prediction, and neuroscience. While often the unexpected emergent behavior of nonlinear systems is the focus of investigations, it is of equal importance to create goal-directed behavior (e.g., stable locomotion from a system of coupled oscillators under perceptual guidance). Modeling goal-directed behavior with nonlinear systems is, however, rather difficult due to the parameter sensitivity of these systems, their complex phase transitions in response to subtle parameter changes, and the difficulty of analyzing and predicting their long-term behavior; intuition and time-consuming parameter tuning play a major role. This letter presents and reviews dynamical movement primitives, a line of research for modeling attractor behaviors of autonomous nonlinear dynamical systems with the help of statistical learning techniques. The essence of our approach is to start with a simple dynamical system, such as a set of linear differential equations, and transform those into a weakly nonlinear system with prescribed attractor dynamics by meansof a learnable autonomous forcing term. Both point attractors and limit cycle attractors of almost arbitrary complexity can be generated. We explain the design principle of our approach and evaluate its properties in several example applications in motor control and robotics.

am

link (url) [BibTex]

link (url) [BibTex]


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Critical Casimir forces along the isofields

Zubaszewska, M., Maciolek, A., Drzewinski, A.

Physical Review E, 88(5), American Physical Society, Melville, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Surface states and the Casimir interaction in the Ising model

Abraham, D. B., Maciolek, A.

Europhysics letters, 101(2), Editrice Compositori., Bologna, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Crystallization, structural diversity, and anisotropy effects in 2D arrays of icosahedral viruses

Fukuto, M., Nguyen, Q. L., Vasilyev, O., Mank, N., Washington-Huges, C. L., Kuzmenko, I., Checco, A., Mao, Y., Wang, Q., Yang, L.

Soft Matter, 9(40):9633-9642, Royal Society of Chemistry, Cambridge, UK, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Dynamics of nanodroplets on structured surfaces

Rauscher, M.

In Nanodroplets, 18, pages: 143-167, Lecture Notes in Nanoscale Science and Technology, Springer, New York, 2013 (incollection)

Abstract
Editors:Zhiming M. Wang

icm

DOI [BibTex]

DOI [BibTex]


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Dynamic arrest in model porous media-intermediate scattering functions

Spanner, Markus, Schnyder, Simon K., Höfling, Felix, Voigtmann, Thomas, Franosch, Thomas

Soft Matter, 9(5):1604-1611, Royal Society of Chemistry, Cambridge, UK, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Zweidimensionale Monte-Carlo-Gittersimulationen im muVT- und NpT-Ensemble

Kirn, Kai Ludwig

Universität Stuttgart, Stuttgart, 2013 (mastersthesis)

icm

[BibTex]

[BibTex]


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Linear response relations in fluctuational electrodynamics

Golyk, V. A., Krüger, Matthias, Kardar, M.

Physical Review B, 88(15), American Physical Society, Woodbury, NY, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Wetting Phenomena on the Nanometer Scale

Rauscher, M., Dietrich, S., Napiórkowski, M.

In Nanoscale Liquid Interfaces - Wetting, Patterning and Force Microscopy at the Molecular Scale, pages: 83-154, Pan Stanford Publishing Pte. Ltd., Singapore, 2013 (incollection)

icm

DOI [BibTex]

DOI [BibTex]


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Ideal Polyethylene Nanocrystals

Osichov, A., Rabe, C., Vogtt, K., Narayanan, T., Harnau, Ludger, Drechsler, M., Ballauff, M.

Journal of the American Chemical Society, 135(31):11645-11650, American Chemical Society, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Permittivity of an inhomogeneous dipolar lattice fluid

Schütz, Christian

Universität Stuttgart, Stuttgart, 2013 (mastersthesis)

icm

[BibTex]

[BibTex]


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Self-Assembly of Two-Dimensional Colloidal Clusters by Tuning the Hydrophobicity, Composition, and Packing Geometry

Law, A. D., Auriol, M., Smith, D., Horozov, T. S., Buzza, D. M. A.

Physical Review Letters, 110, American Physical Society., Woodbury, N.Y., etc., 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Geometry-Induced Superdiffusion in Driven Crowded Systems

Bénichou, O., Bodrova, A., Chakraborty, D., Illien, P., Law, A. D., Mej\’\ia-Monasterio, C., Oshanin, G., Voituriez, R.

Physical Review Letters, 111(26), American Physical Society, Woodbury, N.Y., 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Overshoots in stress-strain curves: Colloid experiments and schematic mode coupling theory

Amann, Christian P, Siebenbürger, Miriam, Krüger, Matthias, Weysser, Fabian, Ballauff, Matthias, Fuchs, Matthias

Journal of Rheology, 57, pages: 149-175, 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Wetting in electrolyte solutions

Ibagon, Ingrid, Bier, Markus, Dietrich, Siegfried

The Journal of Chemical Physics, 138(21), American Institute of Physics, Woodbury, N.Y., 2013 (article)

icm

DOI [BibTex]

DOI [BibTex]


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Learning Objective Functions for Manipulation

Kalakrishnan, M., Pastor, P., Righetti, L., Schaal, S.

In 2013 IEEE International Conference on Robotics and Automation, IEEE, Karlsruhe, Germany, 2013 (inproceedings)

Abstract
We present an approach to learning objective functions for robotic manipulation based on inverse reinforcement learning. Our path integral inverse reinforcement learning algorithm can deal with high-dimensional continuous state-action spaces, and only requires local optimality of demonstrated trajectories. We use L 1 regularization in order to achieve feature selection, and propose an efficient algorithm to minimize the resulting convex objective function. We demonstrate our approach by applying it to two core problems in robotic manipulation. First, we learn a cost function for redundancy resolution in inverse kinematics. Second, we use our method to learn a cost function over trajectories, which is then used in optimization-based motion planning for grasping and manipulation tasks. Experimental results show that our method outperforms previous algorithms in high-dimensional settings.

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Using Torque Redundancy to Optimize Contact Forces in Legged Robots

Righetti, L., Buchli, J., Mistry, M., Kalakrishnan, M., Schaal, S.

In Redundancy in Robot Manipulators and Multi-Robot Systems, 57, pages: 35-51, Lecture Notes in Electrical Engineering, Springer Berlin Heidelberg, 2013 (incollection)

Abstract
The development of legged robots for complex environments requires controllers that guarantee both high tracking performance and compliance with the environment. More specifically the control of contact interaction with the environment is of crucial importance to ensure stable, robust and safe motions. In the following, we present an inverse dynamics controller that exploits torque redundancy to directly and explicitly minimize any combination of linear and quadratic costs in the contact constraints and in the commands. Such a result is particularly relevant for legged robots as it allows to use torque redundancy to directly optimize contact interactions. For example, given a desired locomotion behavior, it can guarantee the minimization of contact forces to reduce slipping on difficult terrains while ensuring high tracking performance of the desired motion. The proposed controller is very simple and computationally efficient, and most importantly it can greatly improve the performance of legged locomotion on difficult terrains as can be seen in the experimental results.

am mg

link (url) [BibTex]

link (url) [BibTex]


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Optimal distribution of contact forces with inverse-dynamics control

Righetti, L., Buchli, J., Mistry, M., Kalakrishnan, M., Schaal, S.

The International Journal of Robotics Research, 32(3):280-298, March 2013 (article)

Abstract
The development of legged robots for complex environments requires controllers that guarantee both high tracking performance and compliance with the environment. More specifically the control of the contact interaction with the environment is of crucial importance to ensure stable, robust and safe motions. In this contribution we develop an inverse-dynamics controller for floating-base robots under contact constraints that can minimize any combination of linear and quadratic costs in the contact constraints and the commands. Our main result is the exact analytical derivation of the controller. Such a result is particularly relevant for legged robots as it allows us to use torque redundancy to directly optimize contact interactions. For example, given a desired locomotion behavior, we can guarantee the minimization of contact forces to reduce slipping on difficult terrains while ensuring high tracking performance of the desired motion. The main advantages of the controller are its simplicity, computational efficiency and robustness to model inaccuracies. We present detailed experimental results on simulated humanoid and quadruped robots as well as a real quadruped robot. The experiments demonstrate that the controller can greatly improve the robustness of locomotion of the robots.1

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Learning Task Error Models for Manipulation

Pastor, P., Kalakrishnan, M., Binney, J., Kelly, J., Righetti, L., Sukhatme, G. S., Schaal, S.

In 2013 IEEE Conference on Robotics and Automation, IEEE, Karlsruhe, Germany, 2013 (inproceedings)

Abstract
Precise kinematic forward models are important for robots to successfully perform dexterous grasping and manipulation tasks, especially when visual servoing is rendered infeasible due to occlusions. A lot of research has been conducted to estimate geometric and non-geometric parameters of kinematic chains to minimize reconstruction errors. However, kinematic chains can include non-linearities, e.g. due to cable stretch and motor-side encoders, that result in significantly different errors for different parts of the state space. Previous work either does not consider such non-linearities or proposes to estimate non-geometric parameters of carefully engineered models that are robot specific. We propose a data-driven approach that learns task error models that account for such unmodeled non-linearities. We argue that in the context of grasping and manipulation, it is sufficient to achieve high accuracy in the task relevant state space. We identify this relevant state space using previously executed joint configurations and learn error corrections for those. Therefore, our system is developed to generate subsequent executions that are similar to previous ones. The experiments show that our method successfully captures the non-linearities in the head kinematic chain (due to a counterbalancing spring) and the arm kinematic chains (due to cable stretch) of the considered experimental platform, see Fig. 1. The feasibility of the presented error learning approach has also been evaluated in independent DARPA ARM-S testing contributing to successfully complete 67 out of 72 grasping and manipulation tasks.

am mg

link (url) DOI [BibTex]

link (url) DOI [BibTex]

2012


Towards Multi-DOF model mediated teleoperation: Using vision to augment feedback
Towards Multi-DOF model mediated teleoperation: Using vision to augment feedback

Willaert, B., Bohg, J., Van Brussel, H., Niemeyer, G.

In IEEE International Workshop on Haptic Audio Visual Environments and Games (HAVE), pages: 25-31, October 2012 (inproceedings)

Abstract
In this paper, we address some of the challenges that arise as model-mediated teleoperation is applied to systems with multiple degrees of freedom and multiple sensors. Specifically we use a system with position, force, and vision sensors to explore an environment geometry in two degrees of freedom. The inclusion of vision is proposed to alleviate the difficulties of estimating an increasing number of environment properties. Vision can furthermore increase the predictive nature of model-mediated teleoperation, by effectively predicting touch feedback before the slave is even in contact with the environment. We focus on the case of estimating the location and orientation of a local surface patch at the contact point between the slave and the environment. We describe the various information sources with their respective limitations and create a combined model estimator as part of a multi-d.o.f. model-mediated controller. An experiment demonstrates the feasibility and benefits of utilizing vision sensors in teleoperation.

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DOI [BibTex]

2012


DOI [BibTex]


Failure Recovery with Shared Autonomy
Failure Recovery with Shared Autonomy

Sankaran, B., Pitzer, B., Osentoski, S.

In International Conference on Intelligent Robots and Systems, October 2012 (inproceedings)

Abstract
Building robots capable of long term autonomy has been a long standing goal of robotics research. Such systems must be capable of performing certain tasks with a high degree of robustness and repeatability. In the context of personal robotics, these tasks could range anywhere from retrieving items from a refrigerator, loading a dishwasher, to setting up a dinner table. Given the complexity of tasks there are a multitude of failure scenarios that the robot can encounter, irrespective of whether the environment is static or dynamic. For a robot to be successful in such situations, it would need to know how to recover from failures or when to ask a human for help. This paper, presents a novel shared autonomy behavioral executive to addresses these issues. We demonstrate how this executive combines generalized logic based recovery and human intervention to achieve continuous failure free operation. We tested the systems over 250 trials of two different use case experiments. Our current algorithm drastically reduced human intervention from 26% to 4% on the first experiment and 46% to 9% on the second experiment. This system provides a new dimension to robot autonomy, where robots can exhibit long term failure free operation with minimal human supervision. We also discuss how the system can be generalized.

am

link (url) [BibTex]

link (url) [BibTex]


Task-Based Grasp Adaptation on a Humanoid Robot
Task-Based Grasp Adaptation on a Humanoid Robot

Bohg, J., Welke, K., León, B., Do, M., Song, D., Wohlkinger, W., Aldoma, A., Madry, M., Przybylski, M., Asfour, T., Marti, H., Kragic, D., Morales, A., Vincze, M.

In 10th IFAC Symposium on Robot Control, SyRoCo 2012, Dubrovnik, Croatia, September 5-7, 2012., pages: 779-786, September 2012 (inproceedings)

Abstract
In this paper, we present an approach towards autonomous grasping of objects according to their category and a given task. Recent advances in the field of object segmentation and categorization as well as task-based grasp inference have been leveraged by integrating them into one pipeline. This allows us to transfer task-specific grasp experience between objects of the same category. The effectiveness of the approach is demonstrated on the humanoid robot ARMAR-IIIa.

am

Video pdf DOI [BibTex]

Video pdf DOI [BibTex]


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Movement Segmentation and Recognition for Imitation Learning

Meier, F., Theodorou, E., Schaal, S.

In Seventeenth International Conference on Artificial Intelligence and Statistics, La Palma, Canary Islands, Fifteenth International Conference on Artificial Intelligence and Statistics , April 2012 (inproceedings)

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link (url) [BibTex]

link (url) [BibTex]


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From Dynamic Movement Primitives to Associative Skill Memories

Pastor, P., Kalakrishnan, M., Meier, F., Stulp, F., Buchli, J., Theodorou, E., Schaal, S.

Robotics and Autonomous Systems, 2012 (article)

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Project Page [BibTex]

Project Page [BibTex]